Vehicles, such as automobiles and trucks for example, include an axle assembly that transmits rotational energy developed by the vehicle engine to the wheels. The axle assembly will typically include a housing having a differential gear set. The differential gear set includes a planetary gear train that allows the wheels of the vehicle to turn at different rotational speeds. This allows an outer wheel to rotate faster than the inner wheel during a turn. The housing typically includes a sump that contains a lubricant. The lubricant is moved by one of the differential gears, such as the ring gear for example, that causes the lubricant to be transferred within the housing to lubricate the components.
In addition to the differential gears, the axle assembly may include other components, such as wheel bearings for example, that may benefit from periodic lubrication. Typically, the axle assembly is arranged to flow oil from the housing into a housing tube that routes the lubricant to the wheel bearings. However, when the vehicle is parked on an inclined surface, the lubricant in the axle tubes may flow under the influence of gravity back to the housing resulting in a less than desired level of lubricant in the axle tube. To accommodate this, the lubricant volume within the sump is increased to maintain the desired lubricant levels in the axle tubes.
Accordingly, it is desirable to provide an axle assembly that maintains a desired level of lubrication to the assembly components while reducing the lubricant volume within the sump.